Field of the Invention
The present invention relates to a stator member and a vacuum pump. Particularly, the present invention relates to a stator member that facilitates thermal radiation from a surface thereof and thermal conduction to an adjacent member, and a vacuum pump that contains the stator member.
Description of the Related Art
Among various vacuum pumps, there are turbomolecular pumps and thread groove type pumps that are often used to form a high vacuum environment.
A chamber for semiconductor manufacturing equipment, a test chamber of an electron microscope, a surface analysis device, a microfabrication device, and the like are the examples of vacuum systems that keep the insides thereof vacuum through an exhaust treatment using those vacuum pumps such as turbomolecular pumps or thread groove type pumps.
Such a vacuum pump for realizing a high vacuum environment has a casing that configures a housing having an inlet port and an outlet port. A structure that exerts an exhaust function of the vacuum pump is accommodated in this casing. This structure exerting an exhaust function is basically configured by a rotary portion (rotor portion) that is supported rotatably and a stator portion that is fixed to the casing.
In case of a turbomolecular pump, a rotary portion thereof has a rotating shaft and a rotating body fixed to the rotating shaft, wherein the rotating body has a plurality of stages of rotor blades (moving blades) disposed radially. The stator portion, on the other hand, has a plurality of stages of stator blades (stationary blades) disposed alternately with respect to the rotor blades.
The turbomolecular pump is also provided with a motor for rotating the rotating shaft at high speed. When the rotating shaft is rotated at high speed through the operation of the motor, gas is introduced through the inlet port by the interaction between the rotor blades and the stator blades and then pumped out from the outlet port.
In this type of vacuum pump, the cylindrical rotary portion that is rotated at high speed is normally made of metal such as aluminum or aluminum alloy. However, for the purpose of achieving better performance (especially in order to rotate the rotary portion at higher speed), a fiber reinforced composite material (fiber reinforced plastics, referred to as “FRP material,” hereinafter) is used recently to manufacture a rotary portion due to its characteristics of lighter weight and higher strength as compared to metal.
Examples of fibers used in the FRP material include aramid fiber (AFRP), boron fiber (BFRP), fiberglass (GFRP), carbon fiber (CFRP), and polyethylene fiber (DI-RP).
Incidentally, in this type of vacuum pump, the rotary portion including the rotary blades that is rotated at high speed often reaches a temperature above 100° C. and equal to or greater than 150° C. due to the exhaust of process gas.
When the rotor portion is continuously rotated at high speed with the rotor portion being heated in this manner, creep phenomena occur, which is a problem in connection with the durability of the rotor portion.
Therefore, the rotor portion needs to be configured to dissipate heat more efficiently. In other words, thermal radiation from the rotor portion and thermal absorption on the surface of the stator portion facing the rotor portion need to be facilitated.
Japanese Patent Application Publication No. 2005-320905 proposes a technology for improving corrosion resistance and heat dissipation properties of a vacuum pump by providing a surface treatment layer configured by a nickel alloy layer and a nickel oxide film to a surface of a component incorporated in the vacuum pump.
Japanese Patent No. 3098139 proposes a technology related to a compound molecular pump in which a rotor of a turbomolecular pump portion is made of metal and a cylindrical rotor of a thread groove pump portion and a supporting plate joining the rotors of these pump portions together are made of FRP, thereby not only improving the exhaust speed and compression ratio of the pump but also reducing the size and weight of the pump.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.